The present invention relates to a power driven hammer drill.
Power driven hammer drills are known in the art and disclosed, for example, in the German Offenlegungsschrift 2,449,191. In known hammer drills, a tool impact mechanism is automatically switched to its operative position when a tool held in a tool holder is placed on a work piece to be worked. This is performed because of a longitudinal displacement of the tool holder, wherein a coupling is actuated for displacement of the tool impact mechanism. For holding the coupling in its engaging position, the user must always overcome the force of a spring which urges the coupling out of its engagement. Clean boring without axially loading of the tool is not possible in the known hammer drills.